I. Field of the Invention
The invention provides a hold down apparatus for a tippable structure of a vehicle having a locking element on the tippable structure and spring loaded lever arrangement which is pivotable relative to the locking element and spring between a released position and a hold down position.
II. Description of the Prior Art
Tippable structures provided on vehicles are generally tiltable around a rear horizontal axis with the help of a hydraulic cylinder which acts on the forward end of the tippable structure. There are also tippable structures which alternatively or additionally can be pivoted about a longitudinal side axis.
There is a problem associated with such structures, namely that--particularly in the empty condition--they are prone to jump around. The resulting noise and wear are understandably undesired.
To overcome these difficulties it is known to hold the structure in its lower position by means of a hold down apparatus.
One such hold down apparatus has a rubber block secured to the vehicle frame by means of a bowl-like housing and a bolt. The rubber block has a central hole which can grip a spherical stud fixed to the tippable structure. The recess in the rubber block is, if necessary, spherical so that the rubber grips around the cylindrical stud and fixes it in position. The problem with this is that, through general wear and upon bending of the spherical stud, its position changes in the course of time and thus it is not held securely in the recess in the rubber block but rather progressively destroys it.
Another known apparatus functions with a hook on the tippable structure, a double lever fixed to the vehicle and a clamping lever impinging on these, which clamping lever is biased into a locking position by a tension spring. A shock absorber is arranged parallel to the spring which rigidly braces the spring when receiving short shocks. This apparatus works as follows. As the tippable structure is lowered the hook descends and twists the double lever from its released position, and in fact into a recess in the hook. The clamping lever then presses the double lever under the action of spring into the locking position and holds it there. The disadvantage of this construction is firstly its large vertical mounting height which prevents it from being used for a riding type vehicle. Furthermore, in this apparatus there is the danger that the interengaging parts will not be in their proper places as the hook descends as a result of wear and misalignment over the course of time, so in this case as well destruction is a possible concern. Even without wear caused by age, difficulties with coupling appear in particular if the vehicle stands on uneven ground and the vehicle frame as well as the tippable structure are bent or twisted in different directions. A further disadvantage of this apparatus is the production costs arising from the required number of constituent parts and the precise manner in which they have to be assembled.